Re: master 242a4b49cb: Minor cleanups to X drag-and-drop code

[Po Lu]

Jashank Jeremy <jashank@rulingia.com.au> writes:

> Whilst chasing down the build failure against e465ea816d, I observed
> some compiler warnings related to this patch:
>
>     .../emacs/src/src/xterm.c:1994:7: warning: variable 'data' is used 
> uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>       if (rc)
>         ^~
>     .../emacs/src/src/xterm.c:2016:7: note: uninitialized use occurs here
>       if (data[1] > XM_DRAG_PROTOCOL_VERSION)
>         ^~~~
>     .../emacs/src/src/xterm.c:1994:3: note: remove the 'if' if its condition 
> is always true
>       if (rc)
>       ^~~~~~~
>     .../emacs/src/src/xterm.c:1977:16: note: initialize the variable 'data' 
> to silence this warning
>       uint8_t *data;
>                  ^
>                   = NULL
>
> This looks like a plausible issue --- XGetWindowProperty looks to be
> fallible, and in the event it fails we're potentially dereferencing an
> uninitialised value.  I suspect the check introduced in this commit
> should be within the immediately preceding region; however, I do not
> know what the implications of such a change would be, and thus won't
> concretely suggest one.

Silly compiler.  If rc is true, tmp_data is always initialized.